WATER-SOLUBLE VITAMINS

Water-soluble vitamins include eight well-recognized members of the vitamin B complex: thiamine, riboflavin, pyridoxine, pantothenic acid, niacin, biotin, folic acid and vitamin B₁₂; the water-soluble essential nutritional factors: choline, inositol, ascorbic acid; and vitamins with less-defined activity for fish: p-aminobenzoic acid, lipoic acid and citrin. The first eight, though required only in small amounts in the diet, play major roles in growth, physiology and metabolism. Choline, inositol and ascorbic acid are required in appreciable quantities in the diet and sometimes are not referred to as vitamins but as major dietary nutrients. A typical vitamin test diet for fish control over the water-soluble vitamins is listed in Table 1.

Table 1 - Water-Soluble Vitamin Test Diet H-440 ^1/

^1/ Diet preparation: Dissolve gelatin in cold water. Heat with stirring on water bath to 80°C. Remove from heat. Add with stirring - dextrin, casein, minerals, oils, and vitamins as temperature decreases. Mix well to 40°C. Pour into containers; move to refrigerator to harden. Remove from trays and store in sealed containers in refrigerator until used. Consistency of diet adjusted by amount of water in final mix and length and strength of beating.

^2/ Delete two parts a -cellulose and add two parts CMC for preliminary feeding

^3/ Dissolve a -tocopherol in oil mix

^4/ Add vitamin B₁₂ in water during final mixing

Thiamine

Experimental avian polyneuritis, a condition resembling beriberi, was produced by Eijkman in Java in 1886 and the anti-beriberi factor was crystallized and named "vitamine". The term "thiamine" was introduced when the chemical nature of the factor was established. Thiamine was isolated from rice polishings in 1926 and synthesized in 1936.

Thiamine hydrochloride is a water-soluble, colourless, monoclinic, crystalline compound. It is comparatively stable to dry heat but is rapidly broken down in neutral or alkaline solutions and is split by sulphites into constituent pyrimidine and thiazole moieties. It has a characteristic yeast-like odour. The pyrimide ring is relatively stable, but the thiazole ring is easily opened by hydrolysis. Several derivatives are stable to heat and appear to be more completely soluble in weak alkaline solutions than thiamine itself and still show biological activity in animals. These derivatives include thiamine propyl disulphide, benzoylthiamine disulphide, dibenzoylthiamine, and benzoylthiamine monophosphate. Both thiamine hydrochloride and thiamine mononitrate have been successfully used as the active vitamin in test diets for fish nutrition studies.

Thiamine is essential for good appetite, normal digestion, growth and fertility. It is needed for normal functioning of the nervous tissue and the requirement is determined by the caloric density of the diet.

Deficiency signs in salmonids include impaired carbohydrate metabolism, nervous disorders, poor appetite, poor growth, and increased sensitivity to shock.

A trunk-winding symptom in eels has been reported, together with haemorrhage at the base of the fins. Skin congestion and subcutaneous haemorrhage occurs in carp fed thiamine-deficient diets. Typical symptoms observed in salmonids, carp and catfish are listed in Table 2. Thiamine deficiency has also been reported in marine flatfish started on clam neck diets stored long enough for thiaminase present to hydrolyze the thiamine in the ration. Typical nervous paralysis occurred with rapid mortality from physical shock.

Table 2 Vitamin Deficiency Syndromes

 

Vitamin	Symptoms in salmon, trout, carp, catfish
Thiamine	Poor appetite, muscle atrophy, convulsions, instability and loss of equilibrium, oedema, poor growth
Riboflavin	Corneal vascularization, cloudy lens, haemorrhagic eyes - photophobia, dim vision, incoordination, abnormal pigmentation of iris, striated constrictions of abdominal wall, dark colouration, poor appetite, anaemia, poor growth
Pyridoxine	Nervous disorders, epileptiform fits, hyperirritability, ataxia, anaemia, loss of appetite, oedema of peritoneal cavity, colourless serous fluid, rapid postmortem rigor mortis, rapid and gasping breathing, flexing of opercles
Pantothenic acid	Clubbed gills, prostration, loss of appetite, necrosis and scarring, cellular atrophy, gill exudate, sluggishness, poor growth
Inositol	Poor growth, distended stomach, increased gastric emptying time, skin lesions
Biotin	Loss of appetite, lesions in colon, colouration, muscle atrophy, spastic convulsions, fragmentation of erythrocytes, skin lesions, poor growth
Folic acid	Poor growth, lethargy, fragility of caudal fin, dark colouration, macrocytic anaemia
Choline	Poor growth, poor food conversion, haemorrhagic kidney and intestine
Nicotinic acid	Loss of appetite, lesions in colon, jerky or difficult motion, weakness, oedema of stomach and colon, muscle spasms while resting, poor growth
Vitamin B12	Poor appetite, low haemoglobin, fragmention of erythrocytes, macrocytic anaemia
Ascorbic acid	Scoliosis, lordosis, impaired collagen formation, altered cartilage, eye lesions, haemorrhagic skin, liver, kidney, intestine, and muscle
p-Aminobenzoic acid	No abnormal indication in growth appetite, mortality

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